In the real-time service, characteristics of an application, for example, characteristics of VoIP (Voice over Internet Protocol) or the like is mapped to each radio bearer (RB), as a QoS-related attribute.
Here, a radio bearer indicates a logical channel that provides QoS to data (packets) transmitted between a base station and a mobile station.
Accordingly, it is assumed that an application type is not estimated in the MAC layer.
HSDPA (High Speed Downlink Packet Access) is configured so that, at each TTI (Transmission Time Interval) through an HS-SCCH (High speed-Shared Control Channel), a mobile station is notified of an assignment of a transmission opportunity to the downlink data addressed to the mobile station.
However, the data is transmitted, for example, once in every tens ms in a characteristic traffic, such as a voice traffic. Accordingly, when a configuration is employed in which the assignment of the transmission opportunity to the data is notified through a channel equivalent to the HS-SCCH, overhead of a signaling channel is made too large to achieve efficiency.
In this regard, in standardization of evolved UTRA, “persistent scheduling” is proposed, in which according to characteristics of the application, the transmission opportunity is assigned to the data used for the application based on a predetermined period. In other words, the persistent scheduling is proposed, in which the data for the application is transmitted at a predetermined timing (for example, see Non-patent Documents 1, 2, and 3).
For example, in the persistent scheduling, as an attribute of the radio bearer whether or not the persistent scheduling is applicable, that is, a period during which the persistent scheduling is performed (persistent scheduling period), is set.
For example, the persistent scheduling period is set based on a frame unit (N×10 msec: N is an integer of N>0).
When the persistent scheduling period is set as “0,” the persistent scheduling is not applied in the radio bearer.
There has also been proposed combined use of such persistent scheduling and a scheduling (usual scheduling) in which a transmission opportunity of data is assigned at each TTI to a mobile station having a preferable radio channel condition.
However, a method has not been proposed wherein an asynchronous HARQ is used as a retransmission control processing when the persistent scheduling is performed.
Moreover, in the conventional persistent scheduling, each mobile station is configured to use a radio resource fixedly assigned to the mobile station when a particular radio bearer is set, and the mobile station communicates by using the particular radio bearer. For this reason, there has been a problem in the conventional persistent scheduling that the radio resource fixedly assigned to the mobile station cannot be changed for each persistent scheduling period.    Non-patent Document 1: Ericsson, R1-060099, “Persistent Scheduling for E-UTRA,” TSG-RAN WG1 LTE AdHoc Helsinki, Finland, Jan. 23-25, 2006    Non-patent Document 2: QUALCOMM Europe, R1-060173, “Considerations for control signalling support of Real Time Services,” 3GPP TSG-RAN WG1 LTE AdHoc, Helsinki, Finland, Jan. 23-25, 2006    Non-patent Document 3: Qualcomm Europe, R2-060550, “Further details on HS-SCCH-less operation for VoIP traffic,” 3GPP TSG-RAN WG2 meeting #51, Denver, Colo., USA, Feb. 13-17, 2006